The present invention relates to a magnetic core.
Conventionally, a reactor, which is a type of induction device, has a pair of cores formed of ferrite with high magnetic permeability and a non-magnetic membrane formed of plastic with low magnetic permeability arranged between the cores to obtain desirable DC superposition characteristics. See, for example, Japanese Laid-open Patent Publication No. 2001-102217.
It is known that a change in the electric current flowing in a coil of an induction device causes heat generation in not only the coil but also cores. However, in the induction device described in the aforementioned document, plastic arranged between the cores, which exhibits a low thermal conductivity, suppresses heat transfer from one of the cores (a first core) to the other one of the cores (a second core). Accordingly, when a cooler is arranged in the first core to radiate heat from the first core, for example, the plastic prevents heat transfer from the second core. The heat is thus easily accumulated in the second core. This problem also occurs in a case in which an air gap is formed between the cores instead of arranging the plastic between the cores.
To solve the problem, the plastic or the air gap may be omitted so that the cores formed of ferrite are allowed to contact each other to facilitate heat transfer from one core to the other. However, in this configuration, improved DC superposition characteristics cannot be obtained.